Starter for electric motors.



vPA'I'ENIED JUNE 23, 1908.

' W.A C. O'BRIEN. STARTER FOR ELECTR MOTGRS. APPLIOATION FILED APB. 9,1907. RENEW!) nomas, 19M.

2 SHEETS-BHEBT 1 Wi im emes PATENTED JUNE 23, 1908.

W. C.'0'BETEN.

STAETEE EUR ELECTRIC MOTORS.

APPLICATION FILED APRV 9, 1907. RENEWED NOV.2Z, 1907.

` 2 SHEETS-SHEET 2.

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attoznuj UNITED sTATEs PATENT oFFroE.

WILLIAM C. OBRIEN, OF BALTIMORE, MARYLAND, ASSIGNOR TO MONITORMANUFACTURING `COMPANY OF BALTIMORE CITY, OF BALTIMORE, MARYLAND, ACORPORATION OF MARY- LAND.

Specification of Letters Patenti Patented June 23, 190s",

Application filed April 9, 1967, Serial No. 367,192. Renewed November`22, 1907. Serial No. 403,342.

To all whom 'it may concern:

Be it known that I, WILLIAM C. OBRIEN, a citizen of the United States,residing at Baltimore, in the State of Maryland, have invented certainnew and'useful Improvements in Starters for Electric Motors, vof whichthe following is a specication.

This invention relates to improvements in automatic starters forelectric motors, of the kind shown in my copending application, SeriqalNo. 333,987, iled September 10, 1906, in which the cutting out of thestarting resistance is regulated by the quantity of current flowing inthe armature circuit.

In the accompanying drawing, Figure 1 is a side elevation, partly insection of] a starter suitable for cutting out a single step or sectionof resistance from the armature circuit, the solenoids of the starterbeing connected in series, and the parts being shown in their normal'positions Fig. 2 is a similar view, showing the positions of the partsat the time the line switch is `first closed and before the current inthe arman ture circuit has fallen to a predetermined quantity; Fig. 3 isa view of a similar starter, with the arts in normal positions, thecoils of the horlding solenoids being connected in shunt to theterminals-'of the line switch, and ,the coils of the regulating solenoidbeing connected in series with the starting resistance and armature, andFig.I 4 is a similar view, of the starter shown in Fig. '3, with theline switch closed and the regulating solenoid and starting resistancecut out.

Referring to Figs. 1 and 2 of the drawing, L and L indicate theterminals of the line or Vsupply circuit and S indicates the lineswitch'for connecting the motor M to the line through the motor starterA. The ar'- mature circuit of the motor extends from the line switch.terminal 1 through conductor 2, solenoid coils 3, conductor 4, solenoidcoils `5, conductor 6, starting resistance 7, conductor 8, stationarycontact 9, thence by conductor-10 to the brush of the armature a andthence by conductor 11 to the line switch terminal 12. The motor shownin the drawing is a shunt wound motor and its field f is connected tothe switch terminals 1 and 12 through conductors 2, 2 and 11. The coils3 and 5 of solenoids B and C, respectively, are ol low resistance andadapted to carry the entire armature'current and the solenoids arevertically arcross bars 13 and 14 of a suitable supporting frameY D. Anarm 15 depends from the lower cross bar of the frame, midway be-4 tweenthe solenoids,'and the lever 16 iscentrally supported on this arm by apivot pin A switch arm 1,8, rigidly connected with the lever 16, isadapted to bemovedl into and out of engagement with the fixed contactpiece 9, according to the direction in which the lever 16 is rocked.AThe switch arm is' connected to the conductor 4, between the coils ofthe solenoids by'a branch conductor 19; When the switch s, formed by theswitch arm 18 and the stationary contact piece 9 is closed, it will benoted that the conductor 19, switch arm and contact pieceform a shuntcircuit around the solenoid O and the resistance 7.

The lever 16 supports at its ends the cores of the solenoids B and O andthe switch s is held normally open Aby the core 20 of the solenoid Bwhich is heavier than the core 21 of the solenoid C. The core 20, madeof solid iron or steel, is not attached to the lever 16 but merely restsupon one end of it, so that the core can. move without moving theleve'r. The core 21 as shown in the draw ing, is -of the same externaldimensions as the core 20, but it is made of tubular iron or steel so asto be lighter than the core 20, and at its lower end the 'core 21 isconnected to the lever 16 by a pin 22 extending through the core andthrough a slot 23 in the lever, Vso that the core and the lever willnecessarily move together.

, The operation of the starter shown in Fig. 1 is as follows: As long asthe line switch S remains in the open position, as shown in saidgure,'the in the positions s Town. As soon as the line switch is closed,current passes through both solenoids, the starting resistance and themotor. The solenoid core 20 is instantly drawn up, as shown in Fig. 2,against a magnet core 24, arranged in the upper end ofthe coil 3 andenergized thereby.A When the core 20 is lifted from-the lever 16 thecore 21 of the solenoid C is left without mechanical support, as s'hownin Fig. 2, and is free to move downward, but the windings of thellatarts of the starter remain ter solenoid are so proportioned that itscore will be held up as ong as the current inthe armature circuit isabove the normal iull 'load current of the armature, or anypredetermined quantity. The switch s, will thus be held open, and theresistance 7 maintained in the armature circuit after thc line switch isclosed, until the current flowing in the armature circuit is reduced toa predetermined safe quantity, by the rotation of thc armature, when thecore 21 will drop and move the lever 16 and the switch arm 18 to closethe switch s. The armature` current will then flow from the terminal 1,around the coils of solenoid B and thence through conductor 19 andswitch s to the armature, thus short circuiting the coils `of solenoid Cand the starting resistance 7. The core 20 will remain up and thelcorel21 will remain down as long as the motor* runs under normal conditions;but when the line switch is opened, 0r the voltage on the line, is,abnormally lowered, the solenoid Bfwillbe deenergize'd or weakened and thecore 20 will drop'ontothe lever and thus force the lever, switch arm andcore 21 back into their nor malpositions, so that the switch s will bein I 1open position and the resistance7 and coils of solenoid C will bein circuit with the armature.

.When the motor starts with a load the current in the armature circuitWill always be suiiicient to raise the core of the holding solenoid whenthe line switch is first closed, and after said core has moved intoengagement with the magnet core 24, it will be supported by the core 24if only a small quantity positions.

of current flows through the armature circuit thereafter. r

.When the motor starts without load, it`

may be desirable, in order to insure the upwardy movement of the core ofthe holding solenoid, to connect the coils of the latter in shuntto theline switch terminals, instead of in series with the motor armature.This is shown in Figs. 3 and 4. In these figures of the drawing, thewire 2, leading from the switch terminal 1 is grounded at 26 on theframe D. From the frame a wire 27 leads to one end ofthe coils 3 oftheholding solenoid B and a conductor 28 extends from the `other end of thesolenoid coils to the opposite switch terminal 12. The regulating soenoid coil is connected in series with the starting resistance andarmature, the coil being connected at one endto the conductor 6, and'atthe other end, by a conductor 29 to the frame of the starter, which iselectrically connected tothe line terminal 1 byi the conductor 2. l f. l

In Fig. 3, the parts are shown in normal When the switch S is closed,the core 20 )um sup, regardless of the quantity of current owing in thearmature circuit; but the'core of the regulating solenoid. re-

`rnains in itsupper position until the quantity, `,of current m thearmat re circuit falls to a predetermined quantit when 1 it drops,

rai-sion, 'a

therebyrocking theswitch arm V18, to closed current then lflows fromconductor 2 to frame I), thence through switch arm 18, stationary'switch member 9, and conductor 1() to the armature, the solenoid C andstart-ing rcsistance being shunted. When the line switch is opened, thecore of the holding solenoid drops onto the lever and re-scts thestarter as shown in Fig. 3.

I claim,-

1. In an automatic starter for electric motors, a starting resistance inthe armature circuit, a regulatingsolenoid having windings in saidcircuit, a switch for cutting out said resistance and windings, saidswitch comprising a lever having one arm connected to the core of theregulating solenoid, and a holding solenoid having its core adapted torest upon the opposite arm of the lever and to support the core of th'eregulating solenoid within its coils and the switch inv open position,said holding solenoid being arranged to lift its core and release thelever when the current is turned on.

2. `In an automatic starter for electric motors, a starting resistancein the armature circuit, a re ulating solenoid having its windings insai circuit, a switch for short-cir- `cuiting said windings andresistance, said switch comprising a lever having one armpivotallyconnected to the core of said solenoid and movable b y theWeight of said core to close the switch whenthe core is released fromits coils, aholding solenoid having a heavier core than the core of saidregulating solenoid said heavy core being adapted to rest loosely uponthe oppositearmof said lever and thereby hold the switch in openposition and the core of thev regulating solenoid in an up yer positionIwhen the current i`s turned o and said holding solenoid being adapted tomove its coreupwardlyfrom the lever when the current is turnedon.

3. In an automatic` starter lfor electric motors, a starting resistancein the armature circuit, a regulating solenoid having its windmgs insaid circuit, a switch for cutting out said resistance and windings,vsaid switch comprising a lever having one arm connected to the core ofthe regulating' solenoid, and a holding solenoid having its'windings inthe armature circuit and having its core adapted -to bear upon theopposite arm ofthe lever and to support theA core of the regulatinsolenoid in an upper position and the switc in open position, saidsolenoid being adapted.

to lift its core and release the lever when the current is turned on.

4. In an automatic starter for electric motors, a starting resistance inthe armature circuit,V a regulating solenoid having its windings in saidcircuit, a switch for shortcircuitI ing said windings and resistance,said switch comprising-a lever havin one arm pivotally connected to thecore o said solenoid and movable by the weight of saidvcore to. close`enigmi theswitch when the core is released from its y coils, a holdingsolenoid having its windings the armature circuit and having a core`heavier than the core of saidregulating solenoid, said heavier corebeing adapted to 'rest looseiy -u on the o posite arni of said lever andthereliny hold ti e switch in onen position and the core of theregulating so enoid in an 'Y 'up er position when the current is turnedoff,

an said holding solenoid being adapted to move its core upwardly fromthe lever when the current is turnedon.

5. inv an autorisatie starter for electric motors, a starting resistancein the armature circuit, a regulating devicel having windings insaidcircuit and having a core or armature,

a switch ier cuttin out said 'resistance and windings, said switc ibeing connected to said core so as to nfiove therewith, anelectromagnetic holding device having a core or armature, andconnections between said cores whereby the core of-'the holdin devicenorinaliy .overbalances the core of t e regulating device and holds theswitch in open position,

said holding device being arranged to lift its ycore from saidconnections when current is l turned on'.

6. In an automatic starter for electric motors, a starting resistance inthe armature circuit, a regulating device having windings in saidcircuit and having a core or armature, a switch for cutting out saidresistance and windings, said switch being connected to said core so asto move therewith, a lever pivotally connected to said core, anelectromagnetic holdin device having a core or armature ada te to bearupon said lever'and to thereby iold the core or armature of theyregulating device inoperative relative to its coils and the switch inopen position, said holdin device being arranged to lift its core and reease the lever when current is turned on.

Iii testimony whereof l aiX my signature, in presence oi two Witnesses.

wiLLniM c. oBRiiiN.

Witnesses n ROBERT WATSON, CLAY JEWELL.

